# Licensed under the Apache License: http://www.apache.org/licenses/LICENSE-2.0
# For details: https://bitbucket.org/ned/coveragepy/src/default/NOTICE.txt

"""Run tests in the farm sub-directory.  Designed for nose."""

import difflib
import filecmp
import fnmatch
import glob
import os
import re
import shutil
import sys
import unittest

from nose.plugins.skip import SkipTest

from unittest_mixins import ModuleAwareMixin, SysPathAwareMixin, change_dir, saved_sys_path
from tests.helpers import run_command
from tests.backtest import execfile         # pylint: disable=redefined-builtin

from coverage.debug import _TEST_NAME_FILE


def test_farm(clean_only=False):
    """A test-generating function for nose to find and run."""
    for fname in glob.glob("tests/farm/*/*.py"):
        case = FarmTestCase(fname, clean_only)
        yield (case,)


# "rU" was deprecated in 3.4
READ_MODE = "rU" if sys.version_info < (3, 4) else "r"


class FarmTestCase(ModuleAwareMixin, SysPathAwareMixin, unittest.TestCase):
    """A test case from the farm tree.

    Tests are short Python script files, often called run.py:

        copy("src", "out")
        run('''
            coverage run white.py
            coverage annotate white.py
            ''', rundir="out")
        compare("out", "gold", "*,cover")
        clean("out")

    Verbs (copy, run, compare, clean) are methods in this class.  FarmTestCase
    has options to allow various uses of the test cases (normal execution,
    cleaning-only, or run and leave the results for debugging).

    This class is a unittest.TestCase so that we can use behavior-modifying
    mixins, but it's only useful as a nose test function.  Yes, this is
    confusing.

    """

    # We don't want test runners finding this and instantiating it themselves.
    __test__ = False

    def __init__(self, runpy, clean_only=False, dont_clean=False):
        """Create a test case from a run.py file.

        `clean_only` means that only the clean() action is executed.
        `dont_clean` means that the clean() action is not executed.

        """
        super(FarmTestCase, self).__init__()

        self.description = runpy
        self.dir, self.runpy = os.path.split(runpy)
        self.clean_only = clean_only
        self.dont_clean = dont_clean
        self.ok = True

    def setUp(self):
        """Test set up, run by nose before __call__."""
        super(FarmTestCase, self).setUp()
        # Modules should be importable from the current directory.
        sys.path.insert(0, '')

    def tearDown(self):
        """Test tear down, run by nose after __call__."""
        # Make sure the test is cleaned up, unless we never want to, or if the
        # test failed.
        if not self.dont_clean and self.ok:         # pragma: part covered
            self.clean_only = True
            self()

        super(FarmTestCase, self).tearDown()

        # This object will be run by nose via the __call__ method, and nose
        # doesn't do cleanups in that case.  Do them now.
        self.doCleanups()

    def runTest(self):
        """Here to make unittest.TestCase happy, but will never be invoked."""
        raise Exception("runTest isn't used in this class!")

    def __call__(self):
        """Execute the test from the run.py file."""
        if _TEST_NAME_FILE:                                 # pragma: debugging
            with open(_TEST_NAME_FILE, "w") as f:
                f.write(self.description.replace("/", "_"))

        # Prepare a dictionary of globals for the run.py files to use.
        fns = """
            copy run runfunc clean skip
            compare contains contains_any doesnt_contain
            """.split()
        if self.clean_only:
            glo = dict((fn, noop) for fn in fns)
            glo['clean'] = clean
        else:
            glo = dict((fn, globals()[fn]) for fn in fns)
            if self.dont_clean:                 # pragma: not covered
                glo['clean'] = noop

        with change_dir(self.dir):
            try:
                execfile(self.runpy, glo)
            except Exception:
                self.ok = False
                raise

    def run_fully(self):        # pragma: not covered
        """Run as a full test case, with setUp and tearDown."""
        self.setUp()
        try:
            self()
        finally:
            self.tearDown()


# Functions usable inside farm run.py files

def noop(*args_unused, **kwargs_unused):
    """A no-op function to stub out run, copy, etc, when only cleaning."""
    pass


def copy(src, dst):
    """Copy a directory."""
    if os.path.exists(dst):
        shutil.rmtree(dst)
    shutil.copytree(src, dst)


def run(cmds, rundir="src", outfile=None):
    """Run a list of commands.

    `cmds` is a string, commands separated by newlines.
    `rundir` is the directory in which to run the commands.
    `outfile` is a file name to redirect stdout to.

    """
    with change_dir(rundir):
        if outfile:
            fout = open(outfile, "a+")
        try:
            for cmd in cmds.split("\n"):
                cmd = cmd.strip()
                if not cmd:
                    continue
                retcode, output = run_command(cmd)
                print(output.rstrip())
                if outfile:
                    fout.write(output)
                if retcode:
                    raise Exception("command exited abnormally")
        finally:
            if outfile:
                fout.close()


def runfunc(fn, rundir="src", addtopath=None):
    """Run a function.

    `fn` is a callable.
    `rundir` is the directory in which to run the function.

    """
    with change_dir(rundir):
        with saved_sys_path():
            if addtopath is not None:
                sys.path.insert(0, addtopath)
            fn()


def compare(
    dir1, dir2, file_pattern=None, size_within=0,
    left_extra=False, right_extra=False, scrubs=None
):
    """Compare files matching `file_pattern` in `dir1` and `dir2`.

    `dir2` is interpreted as a prefix, with Python version numbers appended
    to find the actual directory to compare with. "foo" will compare
    against "foo_v241", "foo_v24", "foo_v2", or "foo", depending on which
    directory is found first.

    `size_within` is a percentage delta for the file sizes.  If non-zero,
    then the file contents are not compared (since they are expected to
    often be different), but the file sizes must be within this amount.
    For example, size_within=10 means that the two files' sizes must be
    within 10 percent of each other to compare equal.

    `left_extra` true means the left directory can have extra files in it
    without triggering an assertion.  `right_extra` means the right
    directory can.

    `scrubs` is a list of pairs, regexes to find and literal strings to
    replace them with to scrub the files of unimportant differences.

    An assertion will be raised if the directories fail one of their
    matches.

    """
    # Search for a dir2 with a version suffix.
    version_suff = ''.join(map(str, sys.version_info[:3]))
    while version_suff:
        trydir = dir2 + '_v' + version_suff
        if os.path.exists(trydir):
            dir2 = trydir
            break
        version_suff = version_suff[:-1]

    assert os.path.exists(dir1), "Left directory missing: %s" % dir1
    assert os.path.exists(dir2), "Right directory missing: %s" % dir2

    dc = filecmp.dircmp(dir1, dir2)
    diff_files = fnmatch_list(dc.diff_files, file_pattern)
    left_only = fnmatch_list(dc.left_only, file_pattern)
    right_only = fnmatch_list(dc.right_only, file_pattern)
    show_diff = True

    if size_within:
        # The files were already compared, use the diff_files list as a
        # guide for size comparison.
        wrong_size = []
        for f in diff_files:
            with open(os.path.join(dir1, f), "rb") as fobj:
                left = fobj.read()
            with open(os.path.join(dir2, f), "rb") as fobj:
                right = fobj.read()
            size_l, size_r = len(left), len(right)
            big, little = max(size_l, size_r), min(size_l, size_r)
            if (big - little) / float(little) > size_within/100.0:
                # print "%d %d" % (big, little)
                # print "Left: ---\n%s\n-----\n%s" % (left, right)
                wrong_size.append("%s (%s,%s)" % (f, size_l, size_r))
        if wrong_size:
            print("File sizes differ between %s and %s: %s" % (
                dir1, dir2, ", ".join(wrong_size)
            ))

        # We'll show the diff iff the files differed enough in size.
        show_diff = bool(wrong_size)

    if show_diff:
        # filecmp only compares in binary mode, but we want text mode.  So
        # look through the list of different files, and compare them
        # ourselves.
        text_diff = []
        for f in diff_files:
            with open(os.path.join(dir1, f), READ_MODE) as fobj:
                left = fobj.read()
            with open(os.path.join(dir2, f), READ_MODE) as fobj:
                right = fobj.read()
            if scrubs:
                left = scrub(left, scrubs)
                right = scrub(right, scrubs)
            if left != right:
                text_diff.append(f)
                left = left.splitlines()
                right = right.splitlines()
                print("\n".join(difflib.Differ().compare(left, right)))
        assert not text_diff, "Files differ: %s" % text_diff

    if not left_extra:
        assert not left_only, "Files in %s only: %s" % (dir1, left_only)
    if not right_extra:
        assert not right_only, "Files in %s only: %s" % (dir2, right_only)


def contains(filename, *strlist):
    """Check that the file contains all of a list of strings.

    An assert will be raised if one of the arguments in `strlist` is
    missing in `filename`.

    """
    with open(filename, "r") as fobj:
        text = fobj.read()
    for s in strlist:
        assert s in text, "Missing content in %s: %r" % (filename, s)


def contains_any(filename, *strlist):
    """Check that the file contains at least one of a list of strings.

    An assert will be raised if none of the arguments in `strlist` is in
    `filename`.

    """
    with open(filename, "r") as fobj:
        text = fobj.read()
    for s in strlist:
        if s in text:
            return
    assert False, "Missing content in %s: %r [1 of %d]" % (filename, strlist[0], len(strlist),)


def doesnt_contain(filename, *strlist):
    """Check that the file contains none of a list of strings.

    An assert will be raised if any of the strings in `strlist` appears in
    `filename`.

    """
    with open(filename, "r") as fobj:
        text = fobj.read()
    for s in strlist:
        assert s not in text, "Forbidden content in %s: %r" % (filename, s)


def clean(cleandir):
    """Clean `cleandir` by removing it and all its children completely."""
    # rmtree gives mysterious failures on Win7, so retry a "few" times.
    # I've seen it take over 100 tries, so, 1000!  This is probably the
    # most unpleasant hack I've written in a long time...
    tries = 1000
    while tries:                    # pragma: part covered
        if os.path.exists(cleandir):
            try:
                shutil.rmtree(cleandir)
            except OSError:         # pragma: not covered
                if tries == 1:
                    raise
                else:
                    tries -= 1
                    continue
        break


def skip(msg=None):
    """Skip the current test."""
    raise SkipTest(msg)


# Helpers

def fnmatch_list(files, file_pattern):
    """Filter the list of `files` to only those that match `file_pattern`.

    If `file_pattern` is None, then return the entire list of files.

    Returns a list of the filtered files.

    """
    if file_pattern:
        files = [f for f in files if fnmatch.fnmatch(f, file_pattern)]
    return files


def scrub(strdata, scrubs):
    """Scrub uninteresting data from the payload in `strdata`.

    `scrubs` is a list of (find, replace) pairs of regexes that are used on
    `strdata`.  A string is returned.

    """
    for rgx_find, rgx_replace in scrubs:
        strdata = re.sub(rgx_find, re.escape(rgx_replace), strdata)
    return strdata


def main():     # pragma: not covered
    """Command-line access to test_farm.

    Commands:

    run testcase ...    - Run specific test case(s)
    out testcase ...    - Run test cases, but don't clean up, leaving output.
    clean               - Clean all the output for all tests.

    """
    try:
        op = sys.argv[1]
    except IndexError:
        op = 'help'

    if op == 'run':
        # Run the test for real.
        for test_case in sys.argv[2:]:
            case = FarmTestCase(test_case)
            case.run_fully()
    elif op == 'out':
        # Run the test, but don't clean up, so we can examine the output.
        for test_case in sys.argv[2:]:
            case = FarmTestCase(test_case, dont_clean=True)
            case.run_fully()
    elif op == 'clean':
        # Run all the tests, but just clean.
        for test in test_farm(clean_only=True):
            test[0].run_fully()
    else:
        print(main.__doc__)

# So that we can run just one farm run.py at a time.
if __name__ == '__main__':
    main()
